Add datree-validation.yml

[datreeio]

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[what-the-diff]

PR Summary

• Trigger workflow on pull request events
  The workflow starts when there is a pull request.
• Check and filter changed files
  It examines the repository to find changed YAML files.
• Install Datree's CLI tool
  Using a curl command, the CLI tool is installed to validate Kubernetes configurations.
• Validate Kubernetes config files
  Only Kubernetes config files are validated according to the organization's policies.